LoudHush is being compatible with the LGPL license of iaxclient so it allows you to run it with other versions of iaxclient.
LoudHush is loading the iaxclient dynamically from the object called iaxclient.dylib located under the Resources folder in the LoudHush application bundle.
To replace the object with a different iaxclient version, you need to:
cd iaxclient/lib make
cd iaxclient/lib/ Change the Makefile shared section to read: $(CC) -single_module -dylib -dynamiclib -o $(DYNLIB) \ $(OBJS) $(DYNLDFLAGS) -framework CoreAudio \ -framework AudioToolbox make shared
LoudHush disables the preference configuration for those codecs that it does not provide (mostly because of license incompatibilities). These include ILBC and others. If you replace libiaxclient with your own version that provides additional codecs, you can tell LoudHush to use the new codecs by directly setting them in the preferences system:
To prevent LoudHush from using one of these codecs, use 0 instead of 1 for the value of the preference key.
Note that using this system to enable codecs that are not present in libiaxclient.dynamic will cause errors.